THE NATURAL HISTORY OF THE MOJAVE FRINGE-TOED LIZARD, UMA SCOPARIA: THE NORTHERN LINEAGE,

AMARGOSA RIVER, CA ____________________________________

A Thesis

Presented to the

Faculty of

California State University, Fullerton

____________________________________

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

in

Biology ____________________________________

By

Jeffery M. Jarvis

Approved by:

Dr. William Presch, Committee Chair Date Department of Biological Science Dr. Sean E. Walker, Member Date Department of Biological Science Dr. William J. Hoese, Member Date Department of Biological Science

ii

ABSTRACT

The Mojave fringe-toed lizard (MFTL), Uma scoparia, is isolated on the

windblown sand dunes of the Mojave Desert. Due to a recent petition to list the

Amargosa River populations as Threatened or Endangered under the Endangered Species

Act, the three northern populations have attracted increased attention, with an emphasis

on the Dumont Dunes population. Dumont Dunes is a compound star dune system (3,885

ha) open to off highway vehicle activity. Also associated with the Amargosa River are

Ibex Dunes and Coyote Holes. Ibex Dunes (688 ha) is protected habitat that is part of

Death Valley National Park. Coyote Holes is a small (20 ha) sandy outcrop found along

the Kingston Wash in protected wilderness.

Uma scoparia were surveyed in 2007 and 2008 by walking transects during

periods of peak activity. Lizards were found from the base of the dunes to the outskirts

of the dune systems, where there was Aeolian sand and scattered vegetation.

MFTLs were observed outside the previously documented ranges, two kilometers

north of the Ibex Dunes population and five kilometers southeast of the Dumont Dunes

population. Vegetation was a necessary habitat requirement, but it was insufficient to

predict lizard occurrence. Observations of lizards decreased from 2007 to 2008, but the

difference was significant only at Ibex Dunes (obs IBX07=26; obs IBX08=3; p=0.011). The

decrease in observations at Dumont Dunes was comparable to U. inornata, while the

reduction in observations at Ibex Dunes was unprecedented. Future surveys should

include mark-recapture techniques to examine population dynamics and dispersal

tendencies.

iii

TABLE OF CONTENTS

ABSTRACT ................................................................................................................... ii LIST OF FIGURES ....................................................................................................... iv ACKNOWLEDGEMENTS ........................................................................................... v Chapter 1. INTRODUCTION ................................................................................................ 1 Natural History: Genus Uma ................................................................................ 1 Natural History: Uma scoparia............................................................................. 3 2. MATERIALS AND METHODS.......................................................................... 8 Study Sites and Transect Placement ..................................................................... 8 Lizard Counting and Plant Cover ......................................................................... 9 Spatial and Statistical Analysis ............................................................................. 11 3. RESULTS ............................................................................................................. 13 Lizard Observations .............................................................................................. 13 Transects ............................................................................................................... 15 Vegetation, Rainfall, and Temperature ................................................................. 15 4. DISCUSSION ....................................................................................................... 17 Lizard Observations .............................................................................................. 17 Food Availability and Rainfall ............................................................................. 19 Future Research and Conservation ....................................................................... 22 Summary of Findings............................................................................................ 25 REFERENCES .............................................................................................................. 44

iv

LIST OF FIGURES

Figure Page

1. Range Map of the Genus Uma .............................................................................. 26

2. Fringes on Hind-foot of Uma scoparia ................................................................. 27

3. Facial Features of U. scoparia .............................................................................. 28

4. Extant populations of U. scoparia and Associated River Drainages .................... 29

5. Populations of Amargosa River Drainage: Transects and Lizard Observations .. 30

6. Dumont Dunes: Transects, Vegetation, and U. scoparia Observations ............... 31

7. Ibex Dunes: Transects, U. scoparia Observations, and Range Extension ............ 32

8. Coyote Holes: Transects and U. scoparia Observations ...................................... 33

9. Field Days and U. scoparia Observations, by Month........................................... 34

10. Sand Temperatures when U. scoparia were Observed ......................................... 35

11. Percent Distribution of Time Periods when U. scoparia were Observed ............. 36

12. Density Measurements of U. scoparia on the Transects ...................................... 37

13. Sand Grain Size Distribution for Samples at Dumont Dunes ............................... 38

14. Large Area of Annual Vegetation at Dumont Dunes ........................................... 39

15. Percent Distribution of Time Periods when Transects were Started .................... 40

16. U. scoparia Observations by BLM, East and Southeast of Dumont Dunes ......... 41

17. Photograph of Arthropods on and Flowers of Petalonyx thurberi ....................... 42

18. Photograph of Blister Beetle Feeding on Tiquilia plicata .................................... 43

v

ACKNOWLEDGEMENTS

Without the help and support of my committee, wife, family, friends, CSU

Fullerton Biology Department, Desert Studies Center, and the Bureau of Land

Management, this thesis could not have been completed. Dr. Sean Walker, Dr. William

Hoese, and Dr. William Presch have been very supportive throughout the process of this

thesis, giving me great feedback, advice, and encouragement; they were always eager to

help in any way they could. In addition, I would like to extend additional thanks to

William Presch for coordinating lodging, showing me around the Mojave Desert, and

sharing many movies and meals together. On the same note, thank you to all of the

regulars at the Desert Studies Center (Eric, Jason, Kelly, Marcello, Ray, and Rob) who

endured me for two summers, putting a roof over my head (Marcello, Rob and Jason),

food in my belly (Eric), and helping me with my fieldwork (Jason, Kelly, Ray and Rob).

A special thank you has to go out to Rob Fulton for coming to the rescue twice while I

was stuck in the sand. Friends and family often gave me great insight and encouragement

when times were rough. My parents provided me with a very flexible job during the off-

season. My greatest appreciation needs to go to my wife, Leanne; she not only supported

me with my field work and crazy schedule, but she also planned our perfect wedding

while I was working.

Four-wheel drive vehicles and fuel were provided by both the Bureau of Land

Management and the Biology Department at CSU Fullerton. Funding, satellite phones,

and miscellaneous field gear were provided by the Bureau of Land Management as part

of the Mojave Fringe-toed Lizard Monitoring Project.

1

CHAPTER 1

INTRODUCTION

Natural History: Genus Uma

Fringe-toed lizards, of the Genus Uma, are highly adapted psammophilous lizards

that inhabit scattered windblown sand habitats in southwestern North America, from

southeastern California to western Arizona and down into north-central Mexico (Norris,

1958; Pough 1974; Schmidt & Bogert, 1947; Williams et al., 1959). The Integrated

Taxanomic Information System (2009) currently recognizes six species of fringe-toed

lizards in North America: the Mojave (MFTL, Uma scoparia), the Coachella Valley (U.

inornata), the Colorado Desert (U. notata), the Yuman Desert (U. rufopunctata), the

Coahuila Desert (U. exsul), and the Chihuahuan Desert (U. paraphygas) fringe-toed

lizards (Figure 1).

Fringe-toed lizards have multiple morphological adaptations for Aeolian habitats.

Scales on the digits are enlarged (Figure 2) to make movement on the sand energy

efficient (Carothers, 1986; Stebbins, 1944). The head has several morphological

adaptations for sand (Figure 3): the lower jaw is counter-sunk into the upper jaw, the

nasal passage is oriented posteriorly, the nasal passage can also be physically constricted,

the eyelids have enlarged ‘eyelash’ scales, and the ears are also covered by enlarged

scales (Stebbins, 1944).

2 Fringe-toed lizards also have interesting behavioral adaptations for their dune

habitat. Most notable is their sand burial behavior, which was described as quiescent by

Pough (1970), meaning the lizards have not been observed to hunt insect prey while

buried or actively move like Chionactis sp. after reaching an optimal depth underneath

the sand. Fringe-toed lizards tend to bury themselves within 4-6 cm of the sand surface

(Norris, 1958; Pough, 1970; Stebbins, 1944). Stebbins (1944) thought the behavior was

thermoregulatory in nature, but Pough (1970) later rejected this hypothesis and thought

that the burial behavior is mainly for cover. While buried, the lizards position their

forelimbs posteriorly along their sides to keep sand from collapsing in around the body

after taking a breath (Pough, 1970).

Diet has varied in studies, but all agree that fringe-toed lizards are opportunistic,

sit-and-wait omnivores. Sand-dwelling invertebrates are an important food item, and the

lizards will feed on flowers and leaves when available (Durtsche, 1995; Kaufmann, 1982

Mayhew, 1966a & b; Stebbins, 1944).

Rainfall has been shown to have an indirect impact on fringe-toed lizard

reproduction (Mayhew, 1966a & b). Food intake is directly linked with testes size in

males, and possibly, female egg production of fringe-toed lizards (Mayhew, 1966a & b).

Winter rain in the Mojave Desert has a positive effect on annual germination in the spring

(Hereford et al., 2006). Increased annual germination provides a greater food source for

ground dwelling arthropods, which results in a larger food supply for insectivorous

animals (Dunham, 1980; Mayhew, 1966a & b; Turner et al., 1982). Mayhew (1966a &

b) suggested that insects associated with perennial vegetation, which bloom later in the

3 season than annuals and are still able to flower during droughts because of deeper,

perennial water sources, serve as a secondary food source. As a result, reproduction in

fringe-toed lizards during drought years is later in the season, producing few juveniles in

the fall (Mayhew 1966 a & b).

Natural History: Uma scoparia

The Mojave fringe-toed lizard (MFTL) is found only in the Mojave Desert where

deposits of fine, windblown sand exist (Figure 4; Mayhew, 1966b; Norris, 1958;

Stebbins, 1944). The habitats of the known populations are associated with present and

historical river drainages and sand fields of the Mojave, Amargosa, and Colorado Rivers

(Enzel et al., 2003).

The Amargosa river populations (San Bernardino County, California) are found at

Ibex Dunes, Dumont Dunes, and Coyote Holes. Ibex Dunes (688 ha, UTM 11 S 557200

m E 3950400 m N) is located east of Saratoga Springs and lies within Death Valley

National Park. Dumont Dunes (3,885 ha, UTM 11 S 570400 m E 3949300 m N) is

southwest of the Kingston Mountains and is an open off-highway vehicle (OHV)

recreation area managed by the Bureau of Land Management (BLM). Coyote Holes (20

ha, UTM 11 S 594400 m E 3944800 m N) is a sandy outcrop within BLM wilderness

found at the southern base of the Kingston Mountains along the Kingston Wash (Norris,

1958; Pough, 1974).

The Mojave River Drainage populations (San Bernardino County, CA; Figure 4)

include Barstow, Lenwood, Pisgah Crater, Coyote Dry Lake, Cronese Dry Lake, Bitter

4 Spring, Red Pass Dry Lake, Silver Dry Lake, Afton Canyon, Rasor Road, Devil’s

Playground, and Kelso Dunes (Murphy et al.¸ 2006; Norris, 1958; Pough, 1974).

Further south, other Mojave fringe-toed lizard populations are found in

Pleistocene discharge channels of the Mojave River, Colorado River, or a channel

connecting both rivers (San Bernardino County, CA unless noted otherwise) (Enzel et al.,

2003). These populations include Amboy Crater, Bristol Dry Lake, Cadiz Dry Lake,

Dale Dry Lake, Rice Valley, Pinto Basin, Palen Dry Lake (Riverside County, CA), Ford

Dry Lake (Riverside County, CA), and Bouse Dunes (La Paz County, Arizona) (Murphy

et al., 2006; Norris, 1958; Pough, 1974).

There is limited literature on the natural history of Uma scoparia. Stebbins

(1944) researched Uma anatomy and ecology, while others have discussed behavior

(Carpenter, 1963; Pough, 1970), evolution and systematics (Norris, 1958; Trepanier &

Murphy, 2001). Reproduction was studied by Mayhew (1966b). More recently the

evolutionary genetics (Gottscho, unpublished; Murphy et al., 2006; Trepanier & Murphy,

2001) and conservation (Center for Biological Diversity & Papadakos-Morafka, 2006;

Jennings & Hayes, 1994; Murphy et al., 2006; Otahal et al., unpublished; United States

Fish and Wildlife Service, 2008) of Uma scoparia have been studied. However, survey

data of U. scoparia is limited and incomplete (Girard, 2004; Morafka, 2003; Otahal et al.,

unpublished).

Girard (2004), which was a continuation of Morafka’s (2003) research, collected

and analyzed survey data of Uma scoparia at El Mirage dry lake, Rasor Road, and

Dumont Dunes. These sites were selected to investigate if off-highway vehicle (OHV)

5 activity has had an effect on these populations. At the Rasor Road population, Girard

also measured and tested predictive variables of Mojave fringe-toed lizard observations.

Data were collected from four 1000 m transects in three varying OHV use areas (low,

medium, and high; total transects varied by site) in June and July of 2003 (Girard, 2004).

Predictive variables that were measured were perennial vegetation, annual vegetation,

‘good’ sand, OHV tire tracks, and rodent burrows. No fringe-toed lizards were seen in

either year at El Mirage Dry Lake (Girard, 2004; Morafka, 2003), and they suggested the

possible extirpation of this population. The results from the 2004 report (Girard) suggest

that ‘good’ sand and rodent burrows were the only predictive variables for observations

of Uma scoparia at Rasor Road. In addition, if the sand and rodent burrows were

removed from the analysis, the only variable (of annuals, perennials, and OHV tracks)

that was predictive of fringe-toed lizard observations was presence of annuals (Girard,

2004). OHV activity at Dumont Dunes did not seem to have an affect on lizard

observations. U. scoparia observations at Dumont Dunes were similar in areas of high

and low OHV activity, but observations were lowest in areas of medium OHV activity

(Girard, 2004; Morafka, 2003).

More surveys like Girard’s and Morafka’s studies should be conducted at the

different populations of Mojave fringe-toed lizards before making management decisions.

Exemplar research would be Barrows (1996, 1997, and 2006) and Chen et al. (2006).

These researchers have surveyed and analyzed extensively at least two populations of the

Federally Threatened Coachella Valley fringe-toed lizard, Uma inornata. They

conducted long term (20 yr) surveys of population dynamics (Barrows, 2006) and

6 constructed predictive modeling on habitat quality and persistence, suggesting for this

species that sand source corridors should be preserved and perches for avian predators

should be avoided (Barrows, 1996, 1997, 2006; Chen et al., 2006). These studies have

been used in management decisions of the Coachella Valley fringe-toed lizard, and

similar long-term monitoring studies on Uma scoparia could aid agencies like the Bureau

of Land Management in making decisions for populations, such as Dumont Dunes.

Despite a lack of survey data and population size estimates, government agencies

recognize Uma scoparia as a species of special concern by California Department of Fish

and Game and a sensitive species by the Bureau of Land Management (BLM) due to the

isolated nature of their habitat (California Department of Fish and Game, 2009; Jennings

and Hayes, 1994). BLM manages most of the lands where U. scoparia can be found, and

they allow OHV activity at some sites where the Mojave fringe-toed lizard occurs.

Recent genetic research has supported the presence of three unique genetic haplotypes of

mitochondrial DNA in the northernmost populations of Mojave fringe-toed lizard, which

include Dumont Dunes, Ibex Dunes, and Coyote Holes (Figure 5) (Murphy et al., 2006).

This led Murphy et al. (2006) to the conclusion that the Amargosa River populations are

a distinct population segment (DPS) in accordance with the Endangered Species Act.

The northern (Amargosa River) populations include Ibex Dunes, Dumont Dunes,

and Coyote Holes (Figure 5). At 3,885 ha, Dumont is over five times larger than Ibex

Dunes (688 ha) and almost 200 times larger than Coyote Holes (20 ha). Dumont Dunes

is open to OHV use, and estimates of OHV activity have exceeded 100,000 people in a

single fiscal year (Bureau of Land Management, 2008).

7

With the recent genetic information and the high levels of OHV activity at the

largest dune system of the Amargosa River drainage, there has been concern by

conservationists and land management about the effects of OHV activity on the fringe-

toed lizard population at Dumont Dunes, and a petition has been sent to the United States

Fish and Wildlife Service (USFWS) to take steps in conserving this DPS (Center for

Biological Diversity & Papadakos-Morafka, 2006; USFWS, 2008; Murphy et al., 2006).

However, most of the information in the petition referenced behaviors, ecology and

conservation of the Coachella Valley (Uma inornata) and Colorado Desert (U. notata)

fringe-toed lizards (Barrows, 1996; Barrows, 1997; Barrows, 2006; Barrows et al., 2005;

Center for Biological Diversity & Papadakos-Morafka, 2006: Chen et al., 2006;

Durtsche, 1995; Luckenbach & Bury, 1983; Pough, 1970; Turner et al., 1984). The

petitioners also assumed that Mojave fringe-toed lizards and high OHV activity overlap

in the same areas (Center for Biological Diversity & Papadakos-Morafka, 2006). Before

government action should be taken at Dumont Dunes, more detailed surveys of the entire

dune system for fringe-toed lizard presence needed to be conducted.

This thesis focuses on surveying the Amargosa River populations more

completely than previously attempted, while identifying any patterns of behavior and

ecology of Uma scoparia.

8

CHAPTER 2

MATERIALS AND METHODS

Study Sites and Transect Placement

Uma scoparia were studied at three sites: Dumont Dunes, Ibex Dunes, and

Coyote Holes (Figure 5). Dumont Dunes are a 3,885 ha compound star dune system

stretching west-to-east, and it has been open to off-highway vehicle activity (OHV) since

the 1960s (Figures 6) (Otahal et al., unplublished). Yearly visitors have grown to over

100,000 people (Bureau of Land Management, 2008). Ibex Dunes (Figure 7) is a 688 ha

dune system that is oriented north-south and is located to the west of Dumont Dunes.

Ibex Dunes are within Death Valley National Park and the Ibex Wilderness area. OHV

activity has been prohibited since 1933 when Death Valley was designated a national

park under the Antiquities Act. Coyote Holes stretches east-west and at 20 ha is

considerably smaller than the other two study sites (Figure 8). It is a sandy outcrop found

within BLM wilderness, along the Kingston Wash about 20 km southeast of Dumont

Dunes. OHV activity at Coyote Holes has been prohibited since the establishment of the

California Desert Protection Act (1944, Public Law 103-433).

This study included 55 transects at Dumont Dunes, 19 transects at Ibex Dunes,

and 4 transects at Coyote Holes (Figure 5). Each transect was 750 m long by 10 m wide

and spaced at least 150 m apart from each other to ensure independence. The transect

9 directionality followed the dominant wind direction (Tinant et al., unpublished). BLM

provided the start and end waypoints for all transects, except for the four transects at

Coyote Holes. The transects at Coyote Holes were established using the same protocol as

the other sites but three out of the four transects needed to be shortened from 750 m to

500 m long due to space limitations. All transects were walked twice during the study,

once in 2007 and again in 2008. The start and end waypoints were uploaded into a

Garmin Rhino 130 GPS/two-way unit, using WGS 1984 datum with 9 m accuracy.

Lizard Counting and Plant Cover

Transects were walked during times of peak activity. The yearly peak activity

falls during the breeding season, which begins in March and ends in July, with highest

activities occurring in May and June (Mayhew, 1966b). Daily activities peaked during

periods when the sand temperatures on the dunes were ideal, ranging between 32oC and

49oC (Norris, 1958; Pough, 1970; Stebbins, 1944). Observational periods varied

depending on sand temperatures, wind, and daylight. Early on in each of the seasons

(March and some of April), there was one long period in which MFTLs were active that

stretched from late morning until early evening. As the season progressed and the sand

temperature rose to 32 oC earlier in the day and remained greater than 32oC later into the

day, the activity window increased until the sand temperatures in the afternoon rose

beyond the thermal limit (>49 oC), effectively dividing the lizard activity period into two

windows. This afternoon divide continued to increase in length until July through August,

when the activity periods are shortest. Transects were walked to maximize ideal sand

temperatures. Occasionally, transects were walked when temperatures were above

10 thermal limits due to time constraints. When conditions were too windy (>20 km/h),

observations were cancelled for the day. Transects were walked in the evenings

occasionally, concluding before sunset.

MFTLs were counted as an observation on a transect only if the lizard originated

within a transect. Lizards seen outside of a transect that then ran into the transect were

not included in calculations. However, all encountered Mojave fringe-toed lizards were

given a waypoint, because of the importance to document where these lizards are active

throughout each location. The waypoints were taken as close as possible to where the

lizards originated. The MFTLs were identified as an adult or juvenile, using Mayhew’s

(1966b) definition of an immature or mature adult having a snout-vent length greater than

50 mm (male and female). The locations of lizards were recorded with the GPS unit.

Before and after walking each transect and whenever a lizard was observed, the sand

temperatures were recorded with a RadioShack infrared thermometer (Cat. No. 22-325).

The temperature at the start and end of each transect was taken on the south-facing slope

of the nearest hummock (highest sand temperature), while the lizard temperatures were

taken as close to where the lizard originated as possible. Potential predators were noted,

along with other species of lizards (e.g., zebra-tailed lizard, whip-tail lizard, and desert

iguana).

The structure of the Uma scoparia habitat was characterized by measuring

vegetation. While walking the transects in 2008, perennial plants were recorded with a

GPS unit, and the presence of annuals was noted. When a MFTL was seen, the nearest

perennial shrub was measured to the nearest half meter by pacing steps or with the GPS

11 device. Due to the potential for error, the GPS device was only used for measuring plants

that were greater than 15 m away from where the lizard was observed. Sand samples

were obtained from each site to analyze grain size and composition. The sand grains

were sorted using a W. S. Tyler Automated Sand Sifter, Model #R-30050. Sand was

sorted into 13 size classes with diameters ranging from 0.053 mm to 0.850 mm.

Elemental composition of the sand samples was determined by Dr. John Foster in the

Geology Department at California State University, Fullerton.

Spatial and Statistical Analysis

Google Earth v.5.0.11337.1968 was used to illustrate patterns of lizard presence.

The imagery data varied and are stated in the figure captions and on the maps (bottom-

center). The lizard data layer was overlaid with satellite photographs and plant data

layers. Polygons representing large expanses of vegetation dominated by flowering

annual from 2008 were estimated using field notes, observations, photographs, and

satellite imagery. Statistical analyses were completed with SPSS v.16.0 and Microsoft

Excel (2003 and 2007).

Data were standardized across all of the dune systems by calculating a density of

lizards seen (MFTL/ha) per transect. The densities were not normally distributed at each

study site; therefore, the means of lizards seen per hectare per transect were compared

between the years at each study site using the Wilcoxon signed ranks test. Comparing

temperature and time from 2007 to 2008, histograms of sand temperatures and time were

prepared for lizard observation and transects. The sand temperatures of when lizards

were observed on transects were analyzed further with a two-sample t-Test assuming

12 equal variance, using the mean difference of start and end transect sand temperatures

from 2007 and 2008. The mean distances from vegetation were calculated for each lizard

seen in 2008. In addition, the number of U. scoparia seen per field day was calculated

for both 2007 and 2008.

13

CHAPTER 3

RESULTS

Lizard Observations

Total Mojave fringe-toed lizards observed, on and off transects, in 2007 and 2008

were 79 and 58 individuals, respectively. Uma scoparia were not observed on the large

bare dune faces at Ibex or Dumont Dunes. Based on the areas that were searched,

Dumont Dunes had more patchy observations (Figure 6). Groups of observations

occurred in both years and were focused in the western, southern, and eastern areas of

Dumont Dunes (Figure 6). There were 17 transects at Dumont Dunes that had zero

vegetation present (Figure 6). All of these transects and the barren dune slopes in

between had zero observations of Uma scoparia. At Dumont Dunes, there were large

areas with zero fringe-toed lizard observations, with 37 out of the 55 (67.3%) transects at

Dumont Dunes not having a lizard observation in either year (Figure 6). Similar habitat

to areas where the fringe-toed lizards were found extend further south and east than

where I surveyed at Dumont Dunes.

At Ibex Dunes, 13 out of the 19 (68.4%) transects had a lizard observation in at

least one year. Fringe-toed lizards were found throughout Ibex Dunes in 2007 and

primarily in the south and northeast in 2008. No transects at Ibex Dunes had lizards

observed on them in both years, but there was one grouping in the southwest with

14 multiple observations on and off transects in both years (Figure 7). An individual was

found two kilometers north of the dune field, expanding the previously known range of

the U. scoparia population at Ibex Dunes (Figure 7).

Coyote Holes produced very few fringe-toed lizard sightings, but they were

present both years (Figures 8). The sample size was too small to notice any patterns in

observations, except that all fringe-toed lizards were found where the substrate was

windblown sand.

In 2007, 60.76% of the lizards were present on transects (obs 07=49). In 2008,

only 32.76% of the lizards seen were on transects (obs 08=19). There were two juveniles

observed in 2007, while there were none observed in 2008. Field days spent at Dumont

Dunes were 12 in 2007 and 13 in 2008, at Ibex Dunes 6 (2007) and 5 (2008), and at

Coyote Holes 1 (2007) and 2 (2008). The field days and lizard observations varied by

month (Figure 9). The sand temperatures (Figure 10) were not significantly different by

year for lizard sightings. Time of observations (Figure 11) followed the same pattern

each year.

At Ibex Dunes from 2007 to 2008, there was an 88.9% (obs IBX07=27; obs IBX08=3)

reduction in MFTLs observed. This reduction was significant (Wilcoxon signed ranks

test, p=0.011) (Figure 12). Coyote Holes experienced similar reductions in observed

lizards with a 62.5% decline (tot COH07=8, tot COH08=3) in lizards overall, and no MFTLs

were seen on transects in 2008; however, the sample size at Coyote Holes was very

small. More individuals were seen in 2008 overall at Dumont Dunes (tot DUM07=37, tot

DUM08=40), but lizards on transects decreased by 20.0% (obs DUM07=20, obs DUM08=16).

15

Transects

Transects varied in many aspects. The majority substrate type of almost all

transects consisted of windblown sand; however, two transects at Coyote Holes only had

a short section, approximately one-fifth of the 500 m transects, that had Aeolian

substrate. Many of the transects at Ibex and Dumont Dunes were comprised mostly of

the large, barren dune faces (slopes).

The substrate varied from Aeolian sand to coarser grained sand to rocky,

mountainous terrain. The sand samples that were analyzed did not seem to have a

different elemental composition. The grain sizes sorted similarly for samples from Ibex

Dunes, Dumont Dunes and Coyote Holes. The only notable difference in sand grain size

was the sample from southern Dumont Dunes, which had a monodispersed particle size

range of fine grain sand (0.151-0.212 mm) (Figure 13).

Vegetation, Rainfall, and Temperature

The vegetation on transects varied from extensive areas having zero vegetation to

areas with sparsely scattered Larrea tridentata to areas covered with annual vegetation

(predominantly desert primrose and sand verbena). In 2008, lizards seen on transects

averaged 27.89 m (SD=36.93) from the nearest perennial shrub. When looking at all

vegetation (annuals and perennials), the mean distance of lizards seen on transects from

the vegetation is 6.37 m (SD=15.72). There was a large increase in annual vegetation in

2008 (Figure 14).

Rainfall data was collected at the nearest weather station in Baker, CA where the

average annual rainfall was 10.69 cm from 1971 to 2007. Rainfall was below average in

16 2006 and 2007 with 8.13 cm and 3.96 cm of precipitation, respectively. Precipitation in

2008 was above average with 11.66 cm (National Climatic Data Center, 2009).

The sand temperatures recorded when fringe-toed lizards were observed on

transects were 44.2°C (2007) and 41.5°C (2008) (Figure 10). With the evening transects

removed, the time periods when transects were started was about the same (Figure 15).

The mean start times of the day transects were 9:29 AM (2007) and 9:54 AM (2008).

The discrepancy in mean start times between the years was a result of more transects

being walked earlier in the season in 2008 and cooler temperatures in May. The mean

temperature in 2007 in Baker, CA was 27.2°C, while the mean temperature in 2008 for

the same month was 24.7°C (National Climatic Data Center, 2009). These cooler

temperatures could account for the decrease in the mean temperature when Uma scoparia

were observed. In addition, most of the transects at Ibex Dunes in 2008 were walked in

May during these cooler temperatures, while most of the transects at Ibex Dunes in 2007

were walked in June. The mean start sand temperatures at Ibex Dunes are 44.7°C (2007)

and 38.9°C (2008).

The difference between the mean sand temperature at the beginning of transects

with fringe-toed lizard observations at all sites in 2007 and 2008 was 2.76°C, and the

difference between the mean sand temperatures at the end of the transects with lizard

observations at all sites in 2007 and 2008 was 3.32°C. Using these differences as the

hypothesized difference, the temperatures when lizards were observed in 2007 and 2008

were not significantly different (Student’s t test: start, p=0.99; end, p=0.58).

17

CHAPTER 4

DISCUSSION

Lizard Observations

The goal of this study was to identify where Uma scoparia existed at three

locations in the Amargosa River drainage. At Dumont Dunes, the lizards were

concentrated in the western, southern, and eastern areas near the transects (Figure 6).

Zero Mojave fringe-toed lizards were observed on transects that had no vegetation

present. At Ibex Dunes, the lizard observations were scattered throughout the dunes

system in 2007 and only observed in the south and northeast in 2008 (Figure 7). At

Coyote Holes, Uma scoparia were found in low numbers at this small outcrop of

windblown sand (Figure 8).

Lizard observations also resulted in the expansion of the known range at Ibex

(Figure 7) and Dumont Dunes (Figure 16). During an exploratory trip along the historic

Tonopah and Tidewater railroad berm in 2006, a fringe-toed lizard was found in a sandy

area about five kilometers southeast of Dumont Dunes near the Valjean Hills. BLM

biologists took this discovery a step further and expanded the range of the population at

Dumont Dunes to include the Valjean Hills (Figure 16) (Otahal et al., unpublished). In

2007, another exploratory trip to the north of Ibex Dunes yielded a MFTL in a sandy

outcrop two kilometers north of the previous range (Figure 7).

18

The importance of vegetation as cover and a food source for Uma has been

suggested by many (Barrows, 1997 & 2006; Durtsche, 1995; Kaufmann, 1982; Mayhew,

1966a & b; Minnich & Shoemaker, 1972; Pough, 1970), but none of these researchers

documented a fringe-toed lizard’s distance from vegetation. Including lizards both on

and off transects (tot08=55), only one Mojave fringe-toed lizard in 2008 was observed

more than 33 m from vegetation (at Ibex, 69 m). The mean distance from vegetation was

6.37 m for lizards on transects. However, some transects that were walked had

windblown sand and vegetation present, but zero lizards were observed in either year on

these transects. This suggests that vegetation presence is necessary but not sufficient to

define Uma scoparia habitat. If further studies were conducted, I would expect that Uma

scoparia would be found within 100 m of any vegetation, expanding the habitat

requirements beyond Aeolian sand only.

The dominant perennial shrubs encountered in MFTL habitat are creosote bush,

Larrea tridentata, and white bursage, Ambrosia dumosa. Two other perennial shrubs that

were found nearest to observed fringe-toed lizards were sandpaper plant, Petalonyx

thurberi, and saltbush, Atriplex sp. Vegetation, I presume, served as cover from

predators, and the lizards appeared to use the perennial shrubs as refuge from the heat.

Durtsche (1995) found very high amounts, both in quantity and mass, of P. thurberi

flowers in the stomachs of male Uma inornata in the month of May. Durtsche (1995)

suggested that MFTLs may be utilizing this plant as a major food source, especially

mature males during the breeding season as a cheap energy source. This plant was

observed in both years to attract large numbers of arthropods while the flowers were in

19 bloom from April through June (Figure 17). P. thurberi was observed at both Ibex and

Dumont Dunes, but it was not present at Coyote Holes. Similarly, Kaufmann (1982)

observed mature male Uma scoparia regularly feeding on the sand verbena flowers

during the breeding season. Dumont Dunes had large expanses of flowering sand

verbena in 2008 (Figure 16).

When comparing observations in 2007 to 2008 at all study sites, there were fewer

lizards observed in 2008. Dumont Dunes (Wilcoxon signed ranks test, p=0.544) and

Coyote Holes (p=0.317) did not show a significant change between 2007 and 2008.

However, Ibex Dunes did show a significant decrease (p=0.009) in total MFTLs seen

from 2007 to 2008 (tot IBX07=35; tot IBX08=15). The difference is even greater if only

looking at lizard observations on transects (obs IBX07=27; obs IBX08=3, p=0.011). This

large decrease in lizard sighting at Ibex appears to be either an anomaly or a result of a

series of events leading to a large decrease in sightings. These events are discussed in

further detail below, but they consist of effects of drought, differences in times when

transects were walked, differences in temperature, problems with walking transects, or a

combination of these factors.

Food Availability and Rainfall

Mayhew (1966a & b) was able to show that rainfall plays a large part in

determining reproductive success of fringe-toed lizards in the following year. For

example, if rainfall is below average during the winter of 2005-2006, then there will be

less mating occurring during the breeding season of 2006; therefore, there will be fewer

juveniles present in the fall of 2006 and spring of 2007. Mayhew (1966a & b) and others

20 (Hereford et al., 2006; Turner et al., 1982) have discussed that rainfall directly affects

food availability. For Uma notata, testes size in males was directly related to food intake,

and decreased egg production in female Uma scoparia coincided with drought years

(Mayhew, 1966a & b).

Barrows (2006) demonstrated that rainfall correlates with U. inornata population

growth, r = ln(Ni+1/Ni). Applying my data to his model, I get negative population growth

for both Dumont (Ni+1=16, Ni=21, r =-0.27) and Ibex Dunes (Ni+1=3, Ni=26, r =-2.16).

The population growth at Dumont Dunes for 2007 compared similarly to the results of

Barrows (2006) in five different years (r =-0.27 +/- 0.1). Also similar to my study, the

rainfall in all five of these years was below 50 mm. However, the negative population

growth at Ibex Dunes for 2007 was unequalled in 20 years of data by Barrows (2006).

The year that comes closest had a population growth of approximately -1.9, with an

annual rainfall of 20 mm (Barrows, 2006). Rainfall in 2007 was 39.6 mm (National

Climatic Data Center, 2009).

Morafka (2003) found the following numbers of fringe-toed lizards per transect

(1000 m) during a drought year: 0.583 (low OHV), 0.250 (moderate OHV), and 0.500

(high OHV). In comparison, the number of lizards seen per ha at Dumont Dunes in 2007

(Figure 12) is similar to Morafka’s data for low and high OHV activity areas. Girard

(2004) found even fewer Uma scoparia on the transects (post drought) at Dumont Dunes

in both areas of high and low OHV activity, approximately 0.2 fringe-toed lizards per

transect, which is comparable to 0.21 U. scoparia per hectare in 2008 (post drought) at

Ibex Dunes (Figure 12). I am not sure where the transects were placed at Dumont Dunes

21 in these studies or whether they were placed in the same areas in 2003 and 2004, but the

location choice could be why they have low observations on their transects. In 1994 to

1998, Morafka recorded 6.714 fringe-toed lizards per transect at Bitter Spring and 6.156

fringe-toed lizards per transect at Red Pass Dry Lake (Morafka, 2003). I have recorded

5.3 MFTLs/ha (equates to Morafka’s and Girard’s MFTLs per 1000 m) on one transect at

Dumont Dunes and 6.7 MFTLs/ha two different transects (one at Ibex and the other at

Dumont) in 2007.

Rainfall during the winters of 2005-2006 and 2006-2007 was below average, and

two juveniles were observed in 2007 and zero in 2008. These observations are consistent

with Mayhew’s (1966a & b) results that suggest low reproductive output during a

drought. However, I did not sample during the best season (fall) to count juveniles.

There may not have been any juveniles observed in 2008 because of an over-abundant

food supply to facilitate rapid growth before I started collecting data. In January 2009,

five out of six MFTLs that were found in a single field day at Dumont Dunes were

juveniles. Similar relationships with rainfall and reproduction have also been

demonstrated with other desert lizard species (Dunham, 1980; Turner et al., 1982).

Three outbreaks of ground dwelling insects were observed at Dumont Dunes in

the spring of 2008, which included Phodaga alticeps (see below, Figure 18), Say’s stink

bug (Chlorochroa sayi), and pallid-winged grasshoppers (Trimerotropis pallidipennis).

These large insect emergences in 2008 were not observed at Ibex Dunes or Coyote Holes.

Hemipterans and orthopterans like Say’s stink bug and the pallid-winged grasshopper

22 may be linked to reproduction and population growth in fringe-toed lizards (Barrows,

2006; Kaufmann, 1982)

Not recorded in this study was the presence of the fanleaf crinklemat plant,

Tiquilia plicata, but there have been interesting observations made. Durtsche (1995)

found leaves of this plant in the stomach contents of U. inornata, but at the time he was

unaware of secondary compounds found in this plant. Seigler et al. (2005) found that the

cyanogenic glycoside dhurrin is the major secondary compound found in tissue samples

of T. plicata. At Dumont Dunes in 2008, there were many blister beetles, mostly

Phodaga alticeps (Meloidae), walking along the ground feeding on T. plicata (Figure

18). Beetles of the family Meloidae are known to produce cantharidin, a highly toxic

secondary compound that produces blisters when introduced to skin and can lead to death

in mammals if ingested (Moed et al., 2001). Both the plant and the beetles were found in

the same habitat as Uma scoparia. It would be interesting to find out if fringe-toed

lizards consume the beetle and if they are then able to break down the secondary

compounds produced by either the plant or the beetle.

Future Research and Conservation

Recently, a petition (Center for Biological Diversity & Papadakos-Morafka,

2006) was investigated by the United States Fish and Wildlife Service (USFWS) to

decide whether past data warranted listing the northern Mojave fringe-toed lizard

populations as a distinct population segment under the Endangered Species Act (USFWS,

2008). In 2008, USFWS, BLM, and California Department of Fish and Game agreed that

a conservation plan would be appropriate, but listing was not yet warranted. A

23 conservation plan for the Dumont Dunes OHV recreation area was created by BLM in

1990, and it is currently being updated with the Mojave Fringe-toed Lizard Conservation

Plan (Otahal et al., unpublished).

Transects work well for large projects with lots of people to share the workload

(e.g. horned lizard project) or when research methods are limited (e.g. Coachella Valley

fringe-toed lizard) (Barrows, 2006; Wright, 2002); however, walking transects alone was

not ideal for this study. In the field, transects are difficult for one person to stay on the

correct heading, search for lizards, and record data without additional aid. In the BLM

protocol, three people were suggested to manage all the tasks of walking a transect. If a

waypoint was set for every 50-100 m along a transect, then I think it would be easier to

stay on the route, without a third person navigating.

Other problems that arose with transects were that the statistics tended to be

nonparametric, the highly mobile and cryptic nature of fringe-toed lizards, and the

variation in habitat quality. Transects were difficult to analyze statistically because there

were a lot of zeros. Many of the transects passed through non-habitat producing a lot of

zeros in the data. Due to the highly adapted and mobile nature of these lizards, many

lizards were likely missed. These lizards were very difficult to see unless the animal

moved. Fringe-toed lizards were likely alerted to my presence well before I was aware of

theirs, allowing them to move out of my way or enter a burrow. As discussed earlier, the

substrate, vegetation, and elevation can all change very drastically within a single

transect. This variation would be difficult to quantify and standardize. Perhaps a

combination of mark-recapture, walking transects, and quantifying habitat variation

24 would be a better survey technique for this species. Some habitat variations and data that

should be collected include vegetation (annual, biannual, and perennial), sand grain size,

relative slope degree and directionality, abundance of rodent burrows, fecal samples, and

documenting tracks.

Mark-recapture studies to estimate population size would work best by using an

injectible electronic identification microchip (PIT tagging) in a mark-recapture study

(Whitfield-Gibbons & Andrews, 2004). Despite evidence suggesting that toe clipping

does not affect the running ability of terrestrial lizards (Borges-Landaez & Shine, 2003),

toe clippings should probably be avoided with this species for potential negative effects

on the running ability of these animals. Carothers (1986) demonstrated that removing the

fringes off the toes will reduce acceleration and velocity of Uma scoparia on sand.

Removing entire toes and the effect on fringe-toed lizards has not been demonstrated, but

it should be done prior to any further mark-recapture studies done with toe-clippings.

Paints or dyes also have drawbacks in long term studies due to the skin shedding cycle of

reptiles. Despite relatively high costs, the PIT tags could be a long-term solution to

measure population dynamics at Dumont Dunes and the extent of dispersal within a dune

system.

An exclusion study would be a better way to test the effects of current OHV

activity on the dunes. Several plots of varying OHV activity areas could be blocked off

to take measurement of plant diversity and succession. These exclusion areas should be

compared to areas where lizards are found. Some factors to compare and measure should

include: soil composition, presence of rodent burrows, presence of boulders/large rocks

25 that could be used as cover, and contour/directionality (flat, slope, East-facing, leeward,

etc.). As supported in this thesis and others, the lizards are very dependent on vegetation,

especially annuals when there is rain (Mayhew, 1966a & b; Norris, 1958). As with most

other desert organisms, perennial vegetation becomes vital during drought years

(Durtsche, 1995; Mayhew, 1966a & b).

If studies are to continue at Dumont Dunes, I would recommend putting in a

weather station to measure winter rainfall and ambient temperatures during sampling

periods. Baker, CA was the closest weather station with complete data for the study

period, but the data was not compared with data from Dumont Dunes to see if there was a

correlation.

Summary of Findings

The seasonal and habitat ranges of the Amargosa River populations of the Mojave

fringe-toed lizard are more extensive than previously measured. The population at Ibex

Dunes extends 2 km north from the past range to some small sandy outcrops with

vegetation. The population at Dumont Dunes follows fingers of habitat east to the

Valjean Hills. All of the range expansions occur in protected habitat. The lizards do not

occur on the large dunes faces of Dumont and Ibex Dunes and the northern areas of

Dumont Dunes where vegetation is absent.

Activity varied from 2007 to 2008, especially at Ibex Dunes, but there were many

potentially contributing factors. Windblown sand and a mix of perennial shrubs and

annual vegetation are important habitat requirements for the Mojave fringe-toed lizard,

but vegetation is not predictive. Surveys of fringe-toed lizards would benefit from long

26 term research and incorporating mark-recapture methods into walking the transects. For

the future, management agencies should take these habitat conditions and expanded range

into account when developing mitigation plans.

2727

Figure 1: Distribution of the six recognized species of fringe-toed lizard in the Genus Uma (Phrynosomatidae). This map is projected on a UTM projection grid with a 700 km scale bar. Imagery obtained from Google Earth, courtesy of ©2009 Europa Technologies, Data U.S. Navy, ©2009 Tele Atlas, and Image NASA.

Legend

Uma scoparia

Uma inornata

Uma notata

Uma rufopunctata

Uma paraphygas

Uma exsul

2828

Figure 2: Picture of enlarged scales on right hind foot of adult Uma scoparia. All toes (hind and fore-feet) have posterior-oriented enlarged scales. The 4th digit (shown above) on the hind feet has the largest extensions.

5 mm

2929

Figure 3: Fringe-toed lizards have several facial adaptations for Aeolian life (Uma scoparia pictured). To reduce sand intake when diving into the sand, the lower jaw is counter-sunk below the top jaw, the nasal passages are oriented posteriorly, and a valve can seal the nasal passages shut. The eyelids have enlarged ‘eyelash’ scales to reduce sand irritation. The ear is covered by enlarged scales.

5mm

3030

Figure 4: A map of the extant populations of the Mojave fringe-toed lizard, Uma scoparia. The triangles on the map represent the northmost populations of this species and are the study sites for this project. Each shape corresponds with a Pleistocene river drainage. UTM projection, with a 150 km scale bar. Imagery obtained from Google Earth, courtesy of ©2009 Europa Technologies, Data U.S. Navy, ©2009 Tele Atlas, and Image NASA.

Amargosa River

Mojave River

Colorado River

1 2

4

3

6

5

78

9

1615

1413

1211

10

19

18

20

17

2423

2221

SaltonSea

40

11 S 418333 m E4008202 m N

15

10

Legend

Populations associated with the following river drainages:Amargosa River

1. Ibex Dunes2. Dumont Dunes3. Coyote Holes

Mojave River4. Lenwood5. Barstow6. Coyote Dry Lake7. Bitter Spring8. Red Pass Dry Lake9. Afton Canyon10. Crones Dry Lake11. Rasor Road12. Silver Dry Lake13. Devil’s Playground14. Kelso Dunes15. Pisgah Crater

Mojave andColorado Rivers

16. Amboy Crater17. Bristol Dry Lake18. Cadiz Dry Lake19. Dale Dry Lake20. Pinto Basin21. Palen Dry Lake22. Ford Dry Lake23. Rice Valley

Colorado River24. Bouse Dunes

RiversRoads

3131

Figure 5: The Amargosa River populations of Uma scoparia. The straight, parallel lines represent the transects at each study site. The red transect lines depict the transects with U. scoparia observations only in 2007. The blue lines had U. scoparia observations in 2008 only. The purple lines had U. scoparia sightings in both 2007 and 2008. The black lines did not have U. scoparia sightings in either year. UTM projection with a 12.0 km scale bar. Imagery date: 2005, © 2009 Tele Atlas.

T & T Railroad

Amargosa River Dumont Dunes

Coyote Holes

Ibex Dunes

11 S 550093 m E3956518 m N

127

3232

Figure 6: The Mojave fringe-toed lizard (MFTL) observations in 2007 (white) and 2008 (grey) at Dumont Dunes with flower polygons (pale violet-red) and transect layout (straight parallel lines, see legend for color interpretations). The circular waypoints were lizards seen on the transects, and the square waypoints were lizards seen off of the transects. UTM projection with a 2000 m scale bar. Imagery date: 2005, © 2009 Tele Atlas.

11 S 567128 m E3951338 m N

Transect LegendNo MFTLs Observed

No Vegetation, No MFTLs Observed

MFTL observations in 2007 only

MFTL observations in 2008 only

MFTL observations in 2007 & 2008

3333

Figure 7: The Mojave fringe-toed lizard (MFTL) observations in 2007 (white) and 2008 (grey) at Ibex Dunes with transect layout (straight parallel lines, see legend for color interpretation). The circular waypoints were lizards seen on the transects, and the square waypoints were lizards seen off of the transects. The northernmost waypoint is 2 km north of the main dune field, extending the previously known range of the Ibex Dunes population. UTM projection with 2500 m scale bar. Imagery date: 2005 , © 2009 Tele Atlas.

11 S 550538 m E3954687 m N

Transect LegendNo MFTLs Observed

MFTL observations in 2007 only

MFTL observations in 2008 only

MFTL observations in 2007 & 2008

3434

Figure 8: The Mojave fringe-toed lizard (MFTL) observations in 2007 (white) and 2008 (grey) at Coyote Holes with transect layout (straight rectangles). The circular waypoints were lizards seen on the transects, and the square waypoints were lizards seen off of the transects. UTM projection with 500 m scale bar. Imagery date: 2005 , © 2009 Tele Atlas.

11 S 593224 m E3945544 m N

Transect Legend

No MFTLs Observed

MFTL observations in 2007 only

35

Figure 9: Field days and Mojave fringe-toed lizard (MFTL) observations broken down by month for each field season.

0

5

10

15

20

25

30

35

40

March April May June July

Months

Num

ber o

f MFT

Ls

0

1

2

3

4

5

6

7

8

9

Num

ber o

f Fie

ld D

ays

MFTLs on transects

All MFTLs on and off transects

Field Days

2007 2008

3636

Figure 10: The percent distribution of sand temperatures when Uma scoparia were encountered on transects. The mean temperatures were 44.2 °C (2007) and 41.5 °C (2008). This decrease in sand temperature was not significantly different from the variation in the start (p=0.99) and end (p=0.58) sand temperatures of the transects in which the lizards were seen.

0%

5%

10%

15%

20%

25%

30%

35%

40%

27.1-30.0 30.1-33.0 33.1-36.0 36.1-39.0 39.1-42.0 42.1-45.0 45.1-48.0 48.1-51.0 51.1-54.0 54.1-57.0Sand Temperature (°C)

2007 2008

Perc

enta

ge

Figure 11: The percent distribution of time periods when Uma scoparia were observed, excluding evenings.

37

0%

5%

10%

15%

20%

25%

30%

35%

40%

7:01-8:00 8:01-9:00 9:01-10:00 10:01-11:00 11:01-12:00 12:01-13:00 13:01-14:00 14:01-15:00 15:01-16:00

Time (24 hr)

Perc

enta

ge

2007 2008

3838

Figure 12: Mean numbers of Mojave fringe-toed lizards (MFTLs) seen per hectare per transect at each study site with 95% confidence intervals (obs=MFTLs seen on transects). Lizards were observed from March through July in 2007 and 2008. The 2007 season was a drought year. In 2008, the rainfall was above the average annual rainfall. Lizard observations at Ibex Dunes was significantly different (Wilcoxon signed ranks test, *p=0.011).

0.000.00

0.50

1.00

1.50

2.00

2.50M

FTLs

/ ha

0.48

1.82

0.500.39

0.21

DUMONT DUNES IBEX DUNES COYOTE HOLES

Study Sites

2007 2008

obs=20 obs=16

obs=26 obs=3

obs=1 obs=0

3,885 ha55 transects

688 ha19 transects

20 ha4 transects

*

3939

Figure 13: The sand grain size distribution at Dumont Dunes. The southern Dumont Dunes sample is more monodispersed (in particle size) than the sand sample from north Dumont Dunes. A majority of the sand at both locations is classified as fine or very fine grained sand.

0 %

5 %

10 %

15 %

20 %

25 %

30 %

Sand Grain Size (mm)

Perc

enta

ge o

f Sam

ple

North Dumont South Dumont

* 44.02%

40

Figure 14: Rainfall during the Fall and Winter of 2007-2008 resulted in large expanses of annual blooms throughout the Mojave Desert. Pictured above is a field of annuals in flower at Dumont Dunes. Sand verbena (purple) and desert primroses (white) made up a majority of the flowers present in the dune habitat. This picture was taken in March of 2008. 40

41Figure 15: The percent distribution of time periods when transects were started for each season.

0%

5%

10%

15%

20%

25%

30%

35%

40%

7:01-8:00

8:01-9:00

9:01-10:00

10:01-11:00

11:01-12:00

12:01-13:00

13:01-14:00

14:01-15:00

15:01-16:00

16:01-17:00

17:01-18:00

18:01-19:00

19:01-20:00

20:01-21:00

Time (24 hr)

Perc

enta

ge

2007 2008

4242

Figure 16: Mojave fringe-toed lizard observations east and southeast of Dumont Dunes, to the Valjean Hills. These data were collected by the Bureau of Land Management. UTM projection with 3.50 km scale bar. Imagery date: 2005 , © 2009 Tele Atlas.

11 S 567769 m E3953198 m N

Dumont Dunes

Valjean Hills

43

Figure 17: Dipterans and a crab spider on a sandpaper plant (Petalonyx thurberi) at Dumont Dunes in 2008. There are actually three dipterans in the frame (circled). The flowers of this plant have been found in the stomach contents of Uma inornata (Durtsche, 1995).

Figure 18: A blister beetle (Meloidae), Phodaga alticeps, eating the leaves of the fanleaf crinklemat plant, Tiquilia plicata, at Dumont Dunes in April of 2008. 44

45

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